1) Large yellow loosestrife (Lysimachia punctata), called Fagerfredløs in Norwegian. These yellow flowers spread out once planted. Here is a photo:
2) Royal Purple Smoke Bush (Cotinus coggygria), called parykkbusk in Norwegian. The color of this plant is something to behold--royal purple indeed. It's gorgeous and stands out in any garden.
3) Lupine (Lupinus)--this plant comes in so many gorgeous colors. This is the tutti frutti lupine.
4) Allium (Allium giganteum)--another lovely flower, a bit alien-looking, but worth having.